Reinforced propeller blade



Aug. 27, 1946. J. H. M KEE REINFORCED PROPELLER BLADE Filed July 26,1945' 2 Sheets-Shei 1 INV/ENTOR. I Jamesli. 1316.166

A 770- NEK Aug. 27, 1.946. J. H; M KEE REINFORCED PROPELLER BLADE 2Sheets- Sheet 2 Filed July 26', 1945 INVENTOR; hazeSEMdKe ATTORNEYPatented Aug. 27, 1946 REINFORCED PROPELLER BLADE James HsMcKee, NorthCaldwell, N. J., assignorv to Curtiss-Wright Corporation, a corporationof Delaware Application July 26, 1943, Serial No. 496,232

1 My invention relates to a propeller blade provided with a novelreinforcing arrangement.

My invention has particular reference to a propeller blade formed fromplates disposed in facing relation and forming an interior chamber, eachplate comprising a longitudinally ex-' tending rib formed integrallytherewith, the ribs facing each other and being suitably secureddirectly to each other throughout at least a, part of the length of saidribs.

My invention has further reference to a propeller blade as describedwherein a tapered connecting member bridges the space between and isconnected to the aforesaid ribs.

Various other objects, advantages and features of my invention willbecome apparent from the followin detailed description.

My invention resides in the reinforced propeller blade, combinations andarrangements of the character hereinafter described and claimed.

For an understanding of my invention and for an illustration of one ofthe forms thereof, reference is to be had to the accompanying drawings,in which:

Figure l is a plan View showing a camber propeller plate and an attachedconnecting member as constructed in accordance with my invention;

Fig. 2 is a longitudinal, vertical sectional view of the arrangementshown in Fig. l;

i Fig. 3 is a 1ongitudinal, vertical sectional view showing a hollowpropeller blade as constructed in accordance with my invention;

Fig. 4 is an elevational view showing a connecting member for thepropeller plates;

Fig. 4a is an elevational view showinga feature of the invention;

Fig. 5 is a longitudinal, vertical sectional view showing the thrustplate of my invention;

Figs. 6 and '7 are enlarged, longitudinal, vertical sectional viewsshowing different parts of my novel propeller blade;

'Fig. 8 is a transverse, vertical sectional view take n on the line 88of Fig. 6 looking in the direction of the arrows;

Figs. 9 and 10 are transverse, vertical sectional views taken on therespective lines 99 and Hll0 of Fig. 7 looking in the direction of thearrows; and

Fig. 11 is an enlarged, longitudinal, vertical sectional view showingthe rib arrangement ad-.

jacent the tip of the propeller blade.

Referring to Figs. 1 and 5, I have shown a metallic camber plate C and ametallic thrust plate Tof the general character known in the 4 Claims.(01. 170-159) art for formin a hollow propeller bladeB as shownlin Figs.6-9 inclusive. Y

A illustrated, the camber plate C comprises a tubular shank I havingextending therefrom the plate pro-per 2 which generally is of convexconfiguration, the convexity decreasing in a progressivemanner as theend of the plate is approached whereby said camber plate C defines 'ashallow opening of generally elliptical configuration. The thrust plateT'comprises a plate proper 2a which generally isof ellipticalconfiguration in correspondence with the aforesaid shallow opening ofthe camber platej C and,

, the ribs r and H are formed, as described in the pending applicationof James H. McKee, Serial No. 493,314, filed July 2, 1943, by subjectinguniformly thick planesheets of metal, which form the blank plates forthe respective camber and thrust plates 0 and T herein disclosed, to twoor more milling operations whereby each sheet of metal is longitudinallytapered in such' manner that'the. thickness of each sheet of metaldecreases longitudinally therealong toward the tip of the blade. Themilling cutter is so shaped that, while the tapering operation proceeds,a longitudinal strip of the original sheet of metal remains intact, thisstrip of metal forming the aforesaid rib 1' or H, the ends thereoftoward the left terminating approximately at the respective locations a,Figs. 1, 2, 3, 5 and 6. As a result of the described milling operations,the thickness or height of each of the ribs r and rl increasesprogressively ma direction extending longitudinally along the propellerblade toward the tip thereof. Further, it is desirable that the millingcutter be so shaped that the described operation causes each of the ribsr or rl to be bordered by fillets j as illustrated.

After the blank plates have been milled as scribed above, the camberplate C and the thrust plate T are brought to the finished formhereindisclosed by subjecting each of the partially completed-propeller plateshaving the integral longi-.

tudinal ribs, respectively, to suitable milling, trim- V and TI by asuitable welding operation.

figuration and the twist being imparted to the plate during theoperation last noted all as generally referred to in said pendingapplication Serial No. 493,314, filed July 2, 1943. Thereafter, theaforesaid shallow opening of the camber plate C is, closed by the thrustplate T when the two plates are secured together by weld metal 3 asshown in Figs. 8, 9 and 10 to form the propeller blade. 7

With the form of the invention herein shown, the rim 1' terminates shortof the tapered end of the camber plate C 'a distance d and the rib rlterminates short of the tapered end of the thrust plate T a distance dl.Further, when the two plates and T are properly assembled toform thepropeller blade, facing surfaces of the ribs 1" and TI are in engagementwith each otheror substantially so throughout a distance (12, Figs. 3 7

and 7. Still further, when the two plates 0 and T are assembled asdescribed'immediately above, facing surfaces of said ribs 1" and TI arespaced from each other in a progressively increasing manner from rightto left throughout a distance d3, Fig.- 3. In accordance with theinvention and for a reason hereinafter to be described, material isremoved in suitable manner from the thick end of each rib r and H asdefined by tapered sections t having a length as indicated by the dis.-

tance d2, for example, this being done prior .to the time that theplates C and T are assembled a described above.

4 the sections thereof at the right of said connecting member M, Figs. 3and '7, to secure said last 7 named rib sections directly togetherthroughout Therefore, in order to permit proper assembly .In'accordancewith the'invention, thereis disposed in the space between said facingsurfaces I of the ribs r and TI a connecting or reinforcing I metallicmember, structure or section of metal M,

Fig. 4, which is of suitable tapered configuration so that it will spanthe space between said facing surfaces of the ribs r and rl eitherentirely or substantially when the two plates C and T are assembled inblade-forming relation. Ordinarily,

the connecting member M is separately formed although, with a broaderconcept of the invention,

said member M may be constituted by weld metal,

for example, which is built up between the ribs 1* With a preferred formof the invention, the connecting member M is suitably held in itsintended position on the ribr of the plate 0 prior to the assembly ofsaid plate 0 and the plate T. While said connecting member M is thusheld, it is secured to the rib r in any suitable manner,

for example, by a welded joint wl formed at the engaging or facingsurfaces of said rib 1 and said connecting member M, thisweldedjoint'being produced in any suitable manner, as by metallic arc,resistance or atomic hydrogen'welding. By this operation, the structureshown in Fig. 2 is produced.

Thereupon, the thrust plate T is assembled in proper relation with theplate and connecting member structure illustrated in Fig. 2. As aresult, the rib TI is brought into engagement or close relation with theadjacent surface of the connecting member M and, beyond the member'M,the two ribs 1 and rl are caused to engage each other or to be closelyadjacent each other. 7

yThereupon, the aforesaid rib T! of the thrust plate T is suitablysecured, as by a welding or equivalent operation, to those surfaces ofthe connecting member M and rib r'which it-fac'es.

In the form of the invention shown, although not necessarily, by astitch or'spot welding operation,

of the plates C and T, the material defining said tapered rib sectionsit is removed as described.

The operations described above result in the production of a hollowpropeller blade B wherein the thrust plate T is secured to the camberplate C and wherein the reinforcing structure comprising the ribs r andr1 together with the connecting member M is operatively related to thetw plates to reinforce them. l

The blade reinforcement comprising the ribs r e and 1! together with theconnecting member M raises the natural frequency thereof above the rangeof objectionable frequencies to some extent at least and this decreasesthe amplitude of plate vibration or deflection.

With respect to apropeller blade wherein the interior chamber is sealed,deformation of the airfoil surface may arise due to-the difference ofaerostatic pressures exteriorly and interiorly of the blade, this beingcaused (1) by pressure differences resulting from changes in altitudeand (2) by pressure. differences due to centrifugal action on the air inthe interior blade chamber. The aforesaid blade reinforcement comprisingthe ribs r and 11 together with the connecting member M decreases thisdeformation of the'air'foil surface. a

Entirely independently of the connecting 'member M and the directconnection between the ribs r and 1'! near the tip of the blade, it willbe understood that these ribs serve to stiffen the plates B and C in adesired manner. Further, each of said ribs 1, TI together with theirrespective fillets f serve in a highly advantageous manner as a baseorextended support to which the con necting member M is secured asdescribed.

With respect to the connecting member M hereinbefore described, it willbe noted that the end thereof toward the left, Figs. 2,

unequal length. These recessed arrangements.

are advantageous because lessening stress concentrations and producing amore fiexible joint be tween the propeller plates. i

It shall be understood that my invention is applicable to various formsor types of hollow propeller blades and that it is not to be restrictedto a propeller blade formed from two plates. Thus,

the plates referred to in the claims may be formed from a single pieceof material. 'They need not be separate plates secured together in 3, 4and 6, is cut away or recessed as indicated at m to form a fish suitablemanner, for example, at their edges as illustrated.

While the invention has been described with respect to a certainparticular preferred example which gives satisfactory results, it willbe understood by .those skilled in the art after understanding theinvention, that various changes and modifications may be made withoutdeparting from the spirit and scope of the invention and it is intendedtherefore in the appended claims to cover all such changes andmodifications.

What is claimed as new and desired to be secured by Letters Patent is:

1. A metallic propeller blade comprising plates disposed in facingrelation and forming an interior chamber, a longitudinally extending ribintegrally formed with each of said plates, the taper of each of saidplates decreasing and the height of each of said ribs increasing in adirection extending longitudinally along the propeller blade toward thetip thereof the height and thickness combined being substantially thesame as the thickest part of the respective plates, adjacent facingsurfaces of said ribs being disposed substantially in contact with eachother near the tip of said propeller blade, other facing surfaces ofsaid ribs being substantially spaced apart in a progressively increasingmanner throughout a longitudinal section of the propeller blade removedfrom the tip thereof, a tapered connecting member between the facingsurfaces second named, and metallic fusion bonding means for securingthe facing surfaces first named directly together and for securing saidconnecting member to the facing surfaces second named.

2. A metallic propeller blade comprising plates disposed in facingrelation and forming an interior chamber said plates decreasing inthickness CIT from shank to tip, a longitudinally extending ribintegrally formed with each of said plates and gradually increasing inheight from shank to tip, and means for connecting said plates togetherthrough said ribs, the connection comprising a tapered connectingmember, said means including a fused metallic bond between said memberand ribs.

3. A metallic propeller blade comprising a-tubular shank from whichextend plates disposed in facing relation and forming an interiorchamber, said plates decreasing in thickness from shank to tip, alongitudinally extending rib integrally formed with each of said platesincreasing in height from shank to tip, and means for connecting saidplates together through said ribs, the connection comprising a taperedconnecting member disposed between spaced faces of said ribs and bondedthereto by metallic fusion, one end of said tapered connecting memberterminating closely adjacent the tip of said propeller blade but shortof the tip end of said ribs, said ribs beyond said member being incontact with one another and bonded together by metallic fusion and theother end of said tapered connecting member being spaced a substantialdistance from said tubular shank.

